There is a conventionally known manufacturing method of a retreaded, or recapped, tire in which the tire assembly is formed of abase tire, which is the base for the tire, and a tread rubber, which is disposed around the periphery of the base tire to come in contact with the road surface. In this method, a buffing operation is first carried out to abrade the outer periphery of a tire away. Then a tread rubber is wound around the buffed surface of the tire after the buffing operation, and the tire is placed in a curing unit. Thus a retreaded tire is obtained as a finished product of a base tire and new tread rubber integrated with each other.
For example, Patent Document 1 proposes a retreaded tire for aircraft featuring a cushion rubber, consisting of a lower rubber layer and an upper rubber layer, placed between a belt and a crown protective layer. And the arrangement is such that the stress occurring when 300% or more of elongation is given to the upper rubber layer is lower than the stress occurring when 300% or more of elongation is given to the lower rubber layer. Besides, the breaking elongation of the upper rubber layer is greater than the breaking elongation of the lower rubber layer. As a result, the interface between the upper rubber layer and the lower rubber layer is made a boundary for easier removal at buffing, thereby preventing the peeling of cushion rubber together with the tread rubber and the crown protective layer.
In the method disclosed in Patent Document 1, however, the buffed surface formed by abrading the tread rubber away is always the surface of the lower rubber irrespective of the repeat count of buffing (repeat count of retreading). Accordingly, the greater the repeat count of retreading, that is, the greater the number of entries in the curing unit, the further the deterioration due to curing of the lower rubber surface, or the buffed surface, will progress. This will lead to a drop in delamination resistance of the cushion rubber and the tread rubber placed on the buffed surface. Eventually this will cause a gradual drop in the durability required of the tire.